I can't speak to the other questions, but Northwestern Stats is not known for any of your listed interests. In fact I do not think they have anyone doing any work in those areas.
I was a graduate student in that department and dropped out due to how uninterested the faculty were, in working with students, and how toxic some faculty members are to their students.
Unless major changes happen, I would not recommend anyone to apply to that department.
Anyone is welcome to DM me if they have questions regarding Northwestern's program.